Sterling farmer is Mr. Clean Greens

STERLING — Crop farming has long been a big part of Michael Koster’s life, always striving to find better ways to get the most out of what he grows.

That ever-growing curiosity has led the Sterling farmer down a different path recently — but it wasn’t a dirt path.

Koster has tapped into the world of hydroponics, a soil-free system where plants are grown primarily in nutrient-rich water, and since dipping his toes in the water, he built a two-bay, gutter-connect greenhouse on his property last year, planted his first seeds in June, and recently begun selling a variety of his leafy greens at local markets..

Koster has grown at least 16 types of vegetables and herbs: lettuces such as regular and red buttercrunch, Batavia, bicolor oak leaf, and mini red and green romaine; as well as arugula, basil, bok choi, chives, cilantro, kale, kohlrabi, parsley, spinach and watercress.

Hydroponic growing is a more efficient way of delivering nutrients to the plants, Koster said.

“The biggest difference is that the plants are grown in water instead of soil,” Koster said. “If you put a plant in soil, the only way you can deliver nutrients is to just dump it on the soil and it becomes the plant’s responsibility to try and reach the nutrients in the soil. We put the nutrients in the water and the water is constantly going to the plant. The nutrients always are available to the plant when they need them.”

It also adds a level of comfort to customers who prefer the transparency of water-based growing, knowing exactly what’s going into their greens, as opposed to the uncertainty of unknown elements that can come from soil-based growing.

“You’re not subject to any contaminants that’s already in the soil,” Koster said. “We’re enclosed here. When stuff is growing out in an open field, you’ll have an animal or a bird that poops on the stuff and it only gets washed off somewhat and gets sold, and that’s a common way E. coli gets into produce.”

Customers also appreciate being able to get fresh greens all year.

“It’s nice to supply the community with a fresh, clean product that you can get year-round,” Koster said. “One of the biggest advantages we have here is the freshness at which we’re able to deliver our product to our customers. When we sell at the farmers every week, what they are buying Saturday morning had been harvested on Friday.”

Koster’s crops can be found on Saturdays at the Twin City Farmers Market in Sterling, as well as at County Market grocery stores in Sterling and Dixon, Oliver’s Corner Market in Dixon, Polo Fresh Market, and Country Lane Market in Tampico. They can also be found in restaurant kitchens at Arthur’s Garden Deli, in Dixon, Sterling, Rock Falls and Rock Island.

The climate-controlled greenhouse measures 44 feet wide by 128 feet long and can hold up to nearly 10,000 different plants. The entire system comes from Cropking of Lodi, Ohio.

The process begins on a table in a room attached to the greenhouse; seeds are planted in moistened rock wool in large trays that are placed under a clear domes and controlled lighting, where they germinate and begin to grow. A heating pad under the trays helps create humidity. While some seeds can’t wait to sprout, others are tougher to crack, especially spinach, which Koster has to nurture to get them soft enough to germinate.

After three days, trays are taken to the nursery section of the greenhouse, placed under grow lights and begin receiving nutrient water for the next 11 days. The sprouts are eventually cut from the rock wool, in small cubes, with each one placed inside a hole on a long-grow channel panel, where they continue to take in water and grow.

Utilizing a nutrient film technique, the nutrient water enters sloped panels through small tubes, about the size of a cell phone charger cord. Excess water is drained out and fed back into the reservoir. As new plants enter the greenhouse, others are moved along until fully grown. Once plants are removed, each panel is cleaned and sanitized before taking on its next batch of budding young plants.

To ensure the water’s consistency, the system is set up with a sample pot that tests pH balance and electrical conductivity. If there’s an imbalance, an automatic system kicks in to restore normal levels.

Having control of the process makes a big difference in the quality of the greens.

“You’re definitely going to be at an advantage as to the healthiness of the crop,” Koster said. “Since we’re able to control most all aspects of the plant, we can make a lot better plants. It’s getting watered all of the time, and it’s getting all of the right nutrients all of the time. When you give a plant everything it needs, it’s going to turn into a very nice looking product.”

Koster’s wife Ally and his mother Anne help with the hydroponic business. Anne works the farmers market table in Sterling and enjoys spreading the word about hydroponics, especially how the process minimizes the environmental footprint and contributes to a greener planet.

“Overall, it’s a very clean, very good way to grow vegetables,” Koster said.

Crops grown inside the hydroponic greenhouses of Koster Farms in rural Sterling are sold year-round at the indoor Twin City Farmers Market, 106 Ave. A in Sterling; it is open from 8 a.m. to noon on Saturday. Find @kosterfarms on Instagram, find Twin City Farmers Market on Facebook or email owner Michael Koster at mkoster14@gmail.com for more information.